Stent graft delivery system with offset tapered tip

ABSTRACT

A stent graft delivery system and method of assembling the same is disclosed. The stent graft delivery system includes a stent graft cover configured to maintain a stent graft in a constricted configuration, and is configured to slide relative to the stent graft to enable the stent graft to expand radially outwardly. The stent graft cover extends along a first central axis. A tapered tip defining an opening therethrough is configured to track along a guidewire. The opening extends along a second central axis that is offset from the first central axis. This provides a delivery system with an opening in a leading edge that is not center relative to the outer stent graft cover.

TECHNICAL FIELD

The present disclosure relates to a delivery system for a stent graft,for example a branched stent graft. In embodiments, the presentdisclosure relates to such a branched stent graft delivery system havingan offset tapered tip.

BACKGROUND

The use of endovascular procedures has been established as a minimallyinvasive technique to deliver a variety of clinical treatments in apatient's vasculature. A stent graft is an implantable device made of atube-shaped surgical graft covering and an expanding or self-expandingmetal frame. The stent graft is placed inside a blood vessel to bridge,for example, an aneurismal, dissected, or other diseased segment of theblood vessel, and, thereby, exclude the hemodynamic pressures of bloodflow from the diseased segment of a blood vessel such as the aorta.

Depending on the region of the aorta involved, the aneurysm may extendinto areas having vessel bifurcations or segments of the aorta fromwhich smaller “branch” arteries extend. For example, thoracic aorticaneurysms can include aneurysms present in the ascending thoracic aorta,the aortic arch, and/or branch arteries that emanate therefrom, such assubclavian or left or right common carotid arteries. In some cases, abranched stent graft can be used to treat such aneurysms. For example, amain stent graft can be deployed in the main vessel (e.g., aortic arch),and a supplemental, secondary stent graft can be deployed in thebranched artery (e.g., left subclavian).

SUMMARY

According to one embodiment, a stent graft delivery system comprises astent graft cover and a tapered tip. The stent graft cover is configuredto maintain a stent graft in a constricted configuration, and configuredto slide relative to the stent graft to enable the stent graft to expandradially outwardly, wherein the stent graft cover extends along a firstcentral axis. The tapered tip defines an opening therethrough that isconfigured to track along a guidewire, wherein the opening extends alonga second central axis that is offset from the first central axis.

According to another embodiment, a stent graft delivery system comprisesa stent graft cover, a tapered tip, a tip capture mechanism, and aspindle. The stent graft cover is configured to maintain a stent graftin a constricted configuration, and configured to slide relative to thestent graft to enable the stent graft to expand radially outwardly. Thetapered tip defines an opening therethrough that is configured to trackalong a guidewire. The tip capture mechanism has an inner member alignedwith the opening, and the inner member has an inner lumen secured to thetapered tip and an outer lumen disposed about the inner lumen andconfigured to slide along an outer surface of the inner lumen. Thespindle is aligned with the opening and has an inner surface contactingthe inner lumen and an outer surface contacting the tapered tip tosecure the tapered tip to the inner lumen.

According to another embodiment, a method of assembling a stent graftdelivery system comprises fitting a barbed spindle about an outersurface of an inner lumen of an inner member, wherein the barbed spindledefines an opening extending about a central axis; press-fitting atapered tip about an outer surface of the barbed spindle, wherein thetapered tip includes an opening extending about the central axis whenpress-fitted to the barbed spindle; and assembling a stent graft coverabout a portion of the tapered tip such that a central axis of the stentgraft cover is offset from the central axis of the opening of the barbedspindle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a stent graft delivery system,according to one embodiment.

FIG. 2 is a rear perspective view of a distal end of the delivery systemwith an inner member removed and a stent graft cover partiallytransparent for view of the inner components, according to oneembodiment.

FIG. 3 is a rear view of the distal end of the delivery system frominside the delivery system, according to one embodiment.

FIG. 4 is a side elevation view of the distal end of the delivery systemwith an opening in the stent graft cover for view of the innercomponents, according to one embodiment.

FIG. 5 is a cross-sectional view of the distal end of the deliverysystem, according to one embodiment.

FIG. 6 is a side view of a spindle configured to be positioned withinthe distal end of the delivery system, according to one embodiment.

FIG. 7 is a side view of the spindle of FIG. 6 placed about an innermember of the delivery system, according to one embodiment.

FIG. 8 is a cross-sectional view of the tapered tip of the deliverysystem having a profile according to one embodiment.

FIG. 9 is a cross-sectional view of the tapered tip of the deliverysystem having a profile according to another embodiment.

FIG. 10 is a cross-sectional view of the tapered tip of the deliverysystem having a profile according to another embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments can take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the embodiments. Asthose of ordinary skill in the art will understand, various featuresillustrated and described with reference to any one of the figures canbe combined with features illustrated in one or more other figures toproduce embodiments that are not explicitly illustrated or described.The combinations of features illustrated provide representativeembodiments for typical applications. Various combinations andmodifications of the features consistent with the teachings of thisdisclosure, however, could be desired for particular applications orimplementations.

Directional terms used herein are made with reference to the views andorientations shown in the exemplary figures. A central axis is shown inthe figures and described below. Terms such as “outer” and “inner” arerelative to the central axis. For example, an “outer” surface means thatthe surfaces faces away from the central axis, or is outboard of another“inner” surface. Terms such as “radial,” “diameter,” “circumference,”etc. also are relative to the central axis. The terms “front,” “rear,”“upper” and “lower” designate directions in the drawings to whichreference is made.

Unless otherwise indicated, for the delivery system the terms “distal”and “proximal” are used in the following description with respect to aposition or direction relative to a treating clinician. “Distal” and“distally” are positions distant from or in a direction away from theclinician, and “proximal” and “proximally” are positions near or in adirection toward the clinician. For the stent-graft prosthesis,“proximal” is the portion nearer the heart by way of blood flow pathwhile “distal” is the portion of the stent-graft further from the heartby way of blood flow path.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description is in the context of treatment ofblood vessels such as the aorta, coronary, carotid and renal arteries,the invention may also be used in any other body passageways where it isdeemed useful.

Thoracic aortic aneurysms with disease progression extending into theaortic arch can be treated with a branched stent graft and deliverysystem. Branched stent graft delivery systems can be used to deliver anddeploy stent grafts that are configured to couple with secondary stentgrafts that extend into vessels or “branches” within a patient'svasculature, such as the thoracic aorta. For example, during a surgicalprocedure, a main guidewire may be fed into the vasculature and into amain vessel (e.g., aortic arch), and a secondary guidewire may be fedinto a secondary vessel or branched artery (e.g., left subclavian). Thestent graft delivery system can include a main lumen that tracks alongthe main guidewire, and a secondary lumen that tracks along thesecondary guidewire. A main stent graft can be deployed in a mainvessel, and a supplemental, secondary stent graft can be deployed in thebranched artery. An example of such a surgical procedure is described inU.S. patent application Ser. No. 16/828,644 titled Branched Stent GraftDelivery System, which is hereby incorporated by reference.

FIG. 1 shows a branched stent graft delivery system 10 according to oneembodiment. The branched stent graft delivery system 10, also moresimply referred to as a stent graft delivery system or a deliverysystem, includes an endovascular catheter and extends between a proximalend 12 and a distal end 14. The terms “proximal end” and “distal end”are not intended to be limiting, as a surgical clinician may, during aprocedure, in fact be located closer to the distal end 14 than theproximal end 12. Therefore, the proximal end and the distal end may bereferred to as a “first end” and a “second end,” respectively.

A threaded screw gear 16 extends along an axis between the proximal end12 and the distal end 14. The threaded screw gear may be a multi-partshell configured to connect together to make a tubular screw gear. Inone embodiment, the screw gear 16 is two half-shells configured toconnect (e.g., snap or assemble) together.

A handle assembly 18 is provided for grip by the clinician. The handleassembly 18 may include two separable portions, namely a front grip 20and an external slider 22. The front grip 20 may be fixed relative tothe screw gear 16, and the external slider 22 may rotate about athreaded outer surface of the screw gear 16 to move linearly along thescrew gear 16. For example, during deployment of a stent graft, theexternal slider 22 is rotated to move toward the proximal end 12. Sincethe external slider 22 is operatively coupled to a stent graft cover 24surrounding the stent graft, the stent graft cover 24 is retracted withthe linear movement of the external slider 22. Meanwhile, a tip 26 atthe distal end 14 of the delivery system 10, which has openings to trackover the guidewires, can remain steady within the vessel as the stentgraft cover 24 is retracted away from the tip 26. Retraction of thestent graft cover 24 allows the stent graft to expand within thepatient's vessel. Once the stent graft is deployed, the entire stentgraft delivery system 10 may be retracted from the patent's vessel.

The stent graft can be self-expanding, in that it includes structuresthat are shaped or formed from a material that can be provided with amechanical memory to return the structure from a compressed orconstricted delivery configuration to an expanded deployedconfiguration. The stent graft can include two main components: atubular graft, and one or more stents for supporting and expanding thegraft. The graft may be formed from any suitable graft material, forexample and not limited to, a low-porosity woven or knit polyester,DACRON material, expanded polytetrafluoroethylene, polyurethane,silicone, or other suitable materials. In another embodiment, the graftmaterial can also be a natural material such as pericardium or anothermembranous tissue such as intestinal submucosa. The stent isradially-compressible and expandable, is coupled to the graft materialfor supporting the graft material, and is operable to self-expand intoapposition with the interior wall of a body vessel (not shown). Eachstent can be constructed from a self-expanding or spring material, suchas but not limited to Nitinol, stainless steel, a pseudo-elastic metalsuch as a nickel titanium alloy or nitinol, various polymers, or aso-called super alloy, which may have a base metal of nickel, cobalt,chromium, or other metal, or other suitable material. This allows thestent graft to expand when the stent graft cover 24 is retractedtherefrom. The stent may be a sinusoidal patterned ring including aplurality of crowns or bends and a plurality of struts or straightsegments with each crown being formed between a pair of opposing struts.

While the screw gear 16 is illustrated and described herein as having athreaded outer surface, it should be understood that in otherembodiments, the screw gear is not threaded, the external slider 22 canslide linearly along the screw gear, or any other suitable mechanism maybe used to retract the graft cover.

The stent graft delivery system 10 may also include an access port 28.The access port 28 provides an opening for insertion, removal, orreceiving of a secondary guidewire lumen, or branching lumen, forsurrounding a secondary guidewire. The delivery system 10 can trackalong both the main guidewire and the secondary guidewire duringdelivery of the stent graft.

FIGS. 2-5 illustrate various views of internal components of a distalend 100 of a stent graft delivery system, such as that illustrated inFIG. 1 . In other words, the structure shown in FIGS. 2-5 and describedbelow can be substituted for the distal end 14 of FIG. 1 .

The distal end 100 includes a tip 102, also referred to as a tapered tipdue to its tapered profile. The tapered tip 102 provides a leading edgeof the delivery system 10, and tracks over one or more guidewires. Inparticular, the tapered tip 102 includes a leading edge or front surface104 that defines a cut-out or opening 106 configured to receive a mainguidewire. The opening 106 can be an aperture in the material of thetapered tip 102 with an inner surface of the tapered tip 102 surroundingthe main guidewire. The opening 106 is aligned with an inner member 108within the stent graft cover 24, as will be described below.

The tapered tip 102 can also include a second opening 110 configured toreceive a secondary guidewire. This second opening 110 allows thedelivery system 10 to track over the secondary guidewire simultaneouslywith the main guidewire. The second opening 110 is aligned with asecondary lumen 112 within the stent graft cover 24, as will bedescribed below.

The stent graft cover 24 is the outer-most sheath or lumen of the stentgraft delivery system. The stent graft cover initially contains orsurrounds a proximal portion of the tapered tip 102, as well as theinner member 108, the secondary lumen 112, and a stent graft (notshown). As explained above, after insertion of the delivery system 10 toa desired location within the patient's vasculature, the surgicaltechnician may utilize the handle to retract the stent graft cover 24,allowing the stent graft to deploy. The stent graft cover 24 is anelongate tubular member defining a lumen from a proximal end to a distalend thereof. The stent graft cover 24 may be formed from a plurality ofdifferent materials or combination of materials; in one embodiment, thestent graft cover 24 is formed with a braided stainless steel wire witha flat or rounded cross section that is sandwiched between layers ofPEBAX® or VESTAMID®.

The inner member 108 defines a hollow lumen, and can be two parts. Forexample, the inner member 108 can include an inner lumen or guidewirelumen 114, and an outer lumen or capture lumen 116. Each of theguidewire lumen 114 and the capture lumen 116 may be made from a hightensile polymer, such as polyether ether ketone (PEEK) or a polyimide.The capture lumen 116 is larger than the guidewire lumen 114 andreceives the guidewire lumen 114 therein. The guidewire lumen 114 may befixed to the tapered tip 102, while the capture lumen 116 may beslideable along the outer surface of the guidewire lumen to slide towardthe proximal end of the delivery system 10. The guidewire lumen 114 maybe fixed in alignment with the opening 106 of the tapered tip 102 toreceive the main guidewire therethrough and track along the mainguidewire during insertion into the patient.

The delivery system also includes a tip capture mechanism, showngenerally at 120. The tip capture mechanism 120 is coupled to, andactuated by, the inner member 108. In particular, according to theillustrated embodiment, the tip capture mechanism 120 includes a capturefitting 122 having a plurality of fingers 124 or prongs. The capturefitting 122 is configured to hold a stent, ring, loop, or other suchstructure of a proximal end of the stent graft. This allows the stentgraft to be deployed (e.g., when the stent graft cover 24 is retracted)while its proximal end is held in a constricted manner duringdeployment. A proximal end of the capture fitting 122 is fixed to thecapture lumen 116 to move with the capture lumen 116. Once the stentgraft is at least partially deployed, the capture lumen 116 can be slidtoward the surgical technician relative to the guidewire lumen 114,thereby releasing the fingers 124 of the tip capture fitting 122 fromthe stent, ring, loop, or the like of the stent graft. This releases thestent graft from the delivery system, and the entire catheter can thenbe removed from the patient. While one example of a tip capturemechanism has been described, any tip capture mechanism may becompatible with the present disclosure. For example, the tip capturemechanism may be configured such that the inner tube extends axiallyforward to move the tip forward relative to the outer tube and spindle,thereby releasing the stent graft. Other tip capture mechanisms mayinclude a single tube, three or more tubes, or other systems.

The secondary lumen 112 is also provided within the stent graft cover24. The secondary lumen 112 is aligned with the opening 110 to receivethe secondary guidewire therethrough, and track along the secondaryguidewire during insertion into the patient's vasculature. The secondarylumen may be located radially outboard of the inner member 108, butradially inward of the stent graft cover 24.

In previous designs of stent graft delivery systems, the addition of asecondary lumen within the confines of the stent graft could presentseveral issues. For example, packaging constraints within the deliverysystem would be compromised, requiring other components within theconfines of the stent graft to be reduced in size while stillmaintaining feasibility. Moreover, a bulge could be created in the stentgraft cover as the secondary lumen is bent around the stent graftcomponents. Such a bulge can make the profile of the delivery systemlager than the intended outer profile. There is also difficulty inmaintaining alignment of the secondary lumen and the inner components.In many cases, the secondary lumen is forced to bend around the arms ofthe capture mechanism and can become bent or misshapen in a way thatcould compromise the lumen patency or at least increase wire frictionthrough the lumen.

Therefore, according to various embodiments described herein, thetapered tip 102 is designed to allow for smaller components within theconfines of the stent graft cover 24. In embodiments, the front surface104 and the opening 106 at the distal end of the tapered tip 102 is notconcentric with the stent graft cover 24. This allows other componentsof the delivery system, such as the inner member 108 and tip capturemechanism 120, to also assume a location that is not concentric with thestent graft cover 24. These components can be offset from center in adirection away from the secondary lumen 112, giving more space for thesecondary lumen 112 to assume and not be bent or create a bulge in thestent graft cover 24. Also, this allows an easier retraction of thesecondary lumen 112, if necessary, during a surgical deployment prior toretraction of the stent graft cover 24.

The nature of the offset can be seen in the FIGS. 4 and 5 , and inparticular FIG. 4 . The distal surface or front surface 104, the opening106, the inner member 108, and the tip capture mechanism 120 are allconcentric and have a common first central axis 130. Meanwhile, thestent graft cover 24 has a second central axis 132 that is offset fromthe first central axis 130. The secondary lumen 112 is positioned towardthe perimeter (e.g., touching or adjacent) of the stent graft cover 24.The first central axis 130 is located away from the second central axis132 in a direction away from the second central axis 132. While theterms “first” and “second” are used herein, it should be understood thatthese terms are used merely to delineate and label the two componentsseparately, and the terms can be interchangeable.

To accommodate for this offset-axis relationship, the internalcomponents may be reduced in size. For example, the tip capturemechanism 120 may be reduced in size, to allow the components to beoffset from their original, central positioning. This creates more spacefor the secondary lumen 112.

This also allows for the tapered tip 102 to be assembled to (e.g.,pressed into) the delivery system late in the assembly process, in whichthe tapered tip 102 can be precisely positioned, rotationally, tooptimize engagement with the secondary lumen 112. In other words, oncethe secondary lumen 112 is assembled and in place within the stent graftcover 24, the tapered tip 102 can be assembled to the remainder of thedelivery system at a rotational alignment such that the opening 110 isaligned with the secondary lumen 112.

To facilitate attachment during assembly, a spindle 140 is provided. Thespindle 140 is a barbed insert for attachment of the tapered tip 102 tothe inner member 108. The spindle 140 is shown in the cross-sectionalview in FIG. 5 , in isolation in FIG. 6 and attached about the guidewirelumen 114 in FIG. 7 . The spindle 140 is configured to align with thetip capture device 120 along the first central axis 130 to hold thestent graft in place during delivery (e.g., the stent apices may be heldbetween the spindle 140 and the capture fitting 122). The spindle 140 isfixed to the tapered tip 102, and does not move with the capture lumen116 or stent graft cover 24 during deployment of the stent graft. Inprevious designs, a spindle was overmolded onto a tapered tip, but thiscan create difficulty with non-concentric arrangements. Instead, inembodiments herein the spindle 140 is a separate component andseparately assembled to the tapered tip 102.

In one embodiment, a portion of the delivery system may be pre-assembledor pre-loaded such that the tapered tip 102 may be assembled to theguidewire lumen 114, which is inserted into the capture lumen 116, andthe tapered tip 102 is pressed onto the spindle 140. This eliminates aneed for any threaded screw fit, and instead provides a simple press-fitattachment between the tapered tip 102 and the spindle 140. The taperedtip 102 may be formed to include an inner surface 142 that creates awidened portion of the opening 106 at a proximal end of the tapered tip102. The inner surface 142 of the widened opening can be pressed aroundand fit about an exterior surface 144 of the spindle 140.

To facilitate the press-fit attachment, the exterior surface 144 of thespindle 140 may be provided with surface features configured to inhibitmovement. In particular, the exterior surface 144 can include a firstset of barbs 146 and a second set of barbs 148. The first set of barbs146 may include one or more fins, projections, or the like that extendannularly about the first central axis 130. As can be seen in FIGS. 6-7, these barbs 146 may be formed to be angled such that a proximal end ofthe barbs 146 extends further radially outward compared to a distal endof the barb 146. This angle inhibits the tapered tip 102 from pullingaway from the spindle 140 after assembly. The barbs 146 may be flattenedor otherwise compressed once the tapered tip 102 is pressed over thebarbs 146.

The second set of barbs 148 may include one or morecircumferentially-spaced fins each extending in an axial direction alongthe exterior surface 144. These barbs 148 are configured to inhibitrotation between the tapered tip 102 and the spindle 140.

To facilitate the press-fit attachment between the guidewire lumen 114and the tapered tip 102, the exterior surface of the guidewire lumen 114may be provided with one or more barbs 150. The barbs 150 may be similarto the first set of barbs 146, being disposed annularly about the firstcentral axis 130. While not shown, the guidewire lumen 114 may also beprovided with one or more barb that is similar in design to the secondset of barbs 148.

As can be seen in FIGS. 4 and 5 , the offset-axis relationship of thedelivery system can yield a tapered tip with varying thicknesses ofmaterial. For example, referring to FIG. 5 , the tapered tip 102 has athicker amount of material above the opening 106 than below. Saidanother way, there is more material of the tapered tip on the side ofthe first central axis 130 closer to the second opening 110 than theother side of the first central axis 130. The first central axis 130 isnot the centerline of the taper of the tapered tip 102. FIGS. 8-10illustrate various embodiments for varying the thickness of the taperedtip on either side of the opening 106. Varying the shape or thickness ofthe tapered tip 102 can provide a preferential bending direction duringinsertion into the vasculature.

The tapered tips of FIGS. 8-10 include the structure of the tapered tip102 described above, unless described otherwise. FIG. 8 shows a taperedtip 102′ according to one embodiment. The tapered tip 102′ has a firstportion 160 on the side of the opening 106 closer to the second opening110, and a second portion 162 on the side of the opening 106 away fromthe second opening 110. The first portion 160 is generally conical inshape, generally constantly increasing in thickness (e.g., between theopening 106 and the outer surface) from the front surface 104 toward therear. The outer surface of the first portion 160 is generally linear.Meanwhile, the second portion 162 has an outer surface that is concave.Therefore, the second portion 162 is not generally conical in shape, asthe thickness of the second portion is not constant. This can influencethe tracking performance of the delivery system in a first manner, witha first preferred bending direction that may allow for easier trackingand device placement.

FIG. 9 shows a tapered tip 102″ according to another embodiment. Thetapered tip 102″ has a first portion 170 on the side of the opening 106closer to the second opening 110, and a second portion 172 on the sideof the opening 106 away from the second opening 110. The first portion170 has an outer surface that is generally concave, and the secondportion 172 has an outer surface that is generally concave. The outersurfaces of the two portions 170, 172 can be pitched or concave atdifferent degrees of magnitude. For example, the second portion 172 canbe more concave than the first portion 170. Moreover, the outer surfacesof both the first and second portions 170, 172 can be angled such thatthe thickness of both portions is equal or substantially similar for atleast a majority of the length of the portions 170, 172. This caninfluence the tracking performance of the delivery system in anothermanner, with another preferred bending direction that may allow foreasier tracking and device placement.

FIG. 10 shows a tapered tip 102′″ according to another embodiment. Thetapered tip 102′″ has a first portion 180 on the side of the opening 106closer to the second opening 110, and a second portion 182 on the sideof the opening 106 away from the second opening 110. The second portion182 may have an outer surface that is generally linear, creating aconical shape of the second portion 182. Meanwhile, the outer surface ofthe first portion 170 may be concave. Opposite to the embodiment of FIG.8 , in this embodiment, the thickness of the second portion 182 mayexceed the thickness of the first portion 180 for at least a majority ofthe length of the portions 180, 182. This can influence the trackingperformance of the delivery system in another manner, with anotherpreferred bending direction that may allow for easier tracking anddevice placement.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The words used in the specification are words of description rather thanlimitation, and it is understood that various changes can be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments can becombined to form further embodiments of the invention that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics can becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes caninclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, to the extentany embodiments are described as less desirable than other embodimentsor prior art implementations with respect to one or morecharacteristics, these embodiments are not outside the scope of thedisclosure and can be desirable for particular applications.

What is claimed is:
 1. A stent graft delivery system comprising: a stentgraft cover configured to maintain a stent graft in a constrictedconfiguration, and configured to slide relative to the stent graft toenable the stent graft to expand radially outwardly, wherein the stentgraft cover extends along a first central axis; a tapered tip defining afirst opening extending within the tapered tip and configured to trackalong a first guidewire and a second opening extending within thetapered tip and configured to track along a second guidewire, whereinthe first opening extends along a first offset axis offset from thefirst central axis; and a tip capture mechanism proximal of the taperedtip and configured to engage the stent graft, wherein the tapered tipincludes a front surface at a leading edge of the stent graft deliverysystem, wherein the first opening is centered with respect to the frontsurface.
 2. The stent graft delivery system of claim 1, wherein thesecond opening extends along a second offset axis offset from the firstoffset axis and the first central axis, the tapered tip includes a crosssection including the first and second offset axes, the cross sectionincludes a first side above the first opening and a second side belowthe first opening.
 3. The stent graft delivery system of claim 2,wherein the first side is thicker than the second side.
 4. The stentgraft delivery system of claim 1, further comprising a secondary lumendisposed within the stent graft cover and aligned with the secondopening to receive the second guidewire therethrough.
 5. The stent graftdelivery system of claim 1, the tip capture mechanism further comprisingan inner member and a plurality of fingers configured to engage thestent graft, wherein the inner member extends along the first offsetsecond central axis.
 6. The stent graft delivery system of claim 5,wherein the inner member includes an inner lumen fixed to the taperedtip, and an outer lumen configured to slide relative to the inner lumen.7. The stent graft delivery system of claim 6, further comprising aspindle disposed about a portion of the inner lumen and press-fit intothe first opening of the tapered tip.
 8. The stent graft delivery systemof claim 7, wherein the spindle includes a plurality of barbs extendingradially outward therefrom, wherein the barbs are configured to inhibitrelative movement between the tapered tip and the spindle.
 9. A stentgraft delivery system comprising: a stent graft cover configured tomaintain a stent graft in a constricted configuration, and configured toslide relative to the stent graft to enable the stent graft to expandradially outwardly, wherein the stent graft cover extends along a firstaxis; a tapered tip at a distal most end of the delivery system defininga first opening extending within the tapered tip and configured to trackalong a first guidewire and a second opening extending within thetapered tip and configured to track along a second guidewire, whereinthe first opening extends along a first offset axis offset from thefirst axis; a tip capture mechanism proximal of the tapered tip andhaving an inner member that extends along the first offset axis, theinner member having an inner lumen secured to the tapered tip and anouter lumen disposed about the inner lumen and configured to slide alongan outer surface of the inner lumen; and a spindle aligned with thefirst opening and having an inner surface contacting the inner lumen andan outer surface contacting the tapered tip to secure the tapered tip tothe inner lumen.
 10. The stent graft delivery system of claim 9, whereinthe spindle is press-fit between the inner lumen and the tapered tip.11. The stent graft delivery system of claim 9, wherein the spindle hasa plurality of surface features on an exterior surface thereof that areconfigured to inhibit relative movement between the spindle and thetapered tip.
 12. The stent graft delivery system of claim 11, whereinthe surface features include one or more annular barbs extending aboutthe first axis thereof and configured to inhibit translational movementbetween the tapered tip and the spindle.
 13. The stent graft deliverysystem of claim 11, wherein the surface features include one or moreaxially-extending barbs circumferentially spaced about the first axisthereof and configured to inhibit rotational movement between thetapered tip and the spindle.
 14. The stent graft delivery system ofclaim 11, wherein the inner lumen includes one or more barbs extendingradially outwardly from an exterior surface thereof, wherein the one ormore barbs are configured to inhibit translational movement between thetapered tip and the inner lumen.